Cycled capsule filling machines have a conveyor wheel, configured as a turntable, for example, on the circumference of which a plurality of capsule holders for accommodating the capsules to be filled is provided. By means of a conveyor wheel drive, the conveyor wheel is moved in cycles along a plurality of process stations disposed along the circumference of the conveyor wheel, the capsule holders passing through the process stations in cycles. Such capsule filling machines form so-called rotary machines. The process stations usually provided include at least one supply station for supplying the capsules to be filled, at least one opening station for opening the capsules to be filled by separating the upper and lower capsule parts, one or more filling stations for filling the lower capsule parts with the respective material, at least one capsule closing station, and at least one capsule discharge station. Furthermore, one or more unused stations can be provided for subsequently adding process stations.
During the cycled conveying of the capsule holders from process station to process station, the conveyor wheel passes through stopping times and movement times. A distinction is made between an indexing time and a holding time. The indexing time defines the time during which the capsule holders are moved from one process station to the next process station. This time is predetermined by the movement time of the conveyor wheel. The holding time defines the time during which the capsule holders are held at the respective process stations to perform the respective process. This time is predetermined by the stopping time of the conveyor wheel.
A machine for filling and closing capsules is known from German Patent Publication No. DE 10 2010 040 505 A1, in which the conveyor wheel is driven by a drive configured as a servomotor. In this manner, the conveying path and the conveying direction are to be variably adjustable during a conveying cycle, for research purposes. The goal there is to reduce the number of drives of the machine to the greatest possible extent. An apparatus for filling capsules is known from European Patent Publication No. EP 1 512 632 B1, in which a filling device is structured as an independent and interchangeable module. The aim is to thus increase the flexibility of the machine. The filling device, configured as a module, possesses its own drive and is mechanically coupled with the machine for operation, and is thereby integrated into the cycled production process.
The cycled movement of the capsule holders is generally implemented by an indexing gear mechanism, which is driven by the conveyor wheel drive. The indexing gear mechanism converts a constant speed of rotation of the conveyor wheel drive into indexing movements, and thus into indexing and holding times. In the indexing gear mechanism, the movement sequence of indexing and holding times is mechanically established by means of suitable cams. A continuously rotating electric motor of the conveyor wheel drive, which drives the indexing gear mechanism, generates a cycle during each of its revolutions via the indexing gear mechanism; in particular, the cycle passes through corresponding indexing angles and holding angles of the cam arrangement. The power take-off of the indexing gear mechanism performs a movement step when the drive passes through the indexing angle, and stands still when the drive passes through the holding angle. The holding and indexing times are therefore established by the holding and indexing angles mechanically implemented in the indexing gear mechanism, and accordingly in principle are in a fixed ratio conforming with the design of the indexing gear mechanism. One mechanical cam disk for controlling the movement sequences in a process station, coupled with the conveyor wheel drive, is generally provided for each process station. Therefore, if the conveyor wheel drive is operated at a different speed of rotation, for example, this accordingly changes the cycle count and the speed of the respective displacement movement of the process stations.
Sometimes it is necessary, for production reasons, to lengthen the holding time of individual process stations. For example, depending on the material to be filled into the capsules, a longer filling time and/or a longer closing time and therefore slower filling or slower closing of the capsules may be necessary. For example, when filling the capsules with a fine-grain powder, attention must be paid during closing to ensure that powder is not undesirably displaced from the capsules by the air displaced during the course of closing. This is less critical, for example, when filling takes place with pellets or tablets that have already been pressed. Also, depending on the respective material and the degree of filling of the capsules, attention must be paid to ensure that the lower capsule parts, which have already been filled, are not moved on too rapidly, in order to prevent the powder from spilling out of the capsules.
Because of the fixed ratio between holding time and indexing time as explained above, the conveyor wheel drive that drives the indexing gear mechanism must be operated more slowly if slower filling is necessary, for example, so that the production by the apparatus is slowed down overall. As a result, the total cycle time composed of holding and indexing times is lengthened. The slowest process station accordingly determines the overall production speed of the machine.
The mechanical coupling between the conveyor wheel drive and the process stations provided for in the state of the art, via the indexing gear mechanism and the mechanical cam disks, also results in disadvantages with regard to installation and setup of the machine. For example, because of the coupling of the drive trains, all the mechanical cam disks must be mechanically coordinated and aligned with one another and with the conveyor wheel in a complicated manner. During the course of setup of the machine, movement of a process station can only take place if the conveyor wheel is also moving. A single process station cannot be moved and adjusted by itself. The mechanical cam disks, once they have been designed, cannot adapt to changing production parameters, for example different speeds of rotation, accelerations or strokes of the individual process stations.